The present invention, generally, relates to airbags and, more particularly, to inflatable airbags for use in vehicles to protect an individual from injury during an accident.
In today's transportation vehicles, particularly automobiles, the use of airbags has become almost second nature with the driving public. Such universal use is due to airbags now being recognized for their injury saving, even life saving, potential.
However, recently an alarming number of injuries have been due to the airbags deploying suddenly and unexpectently, without cause. Usually in such incidents, the force of the deploying airbag itself causes the injury, even death.
Present day airbags have potentially dangerous characteristics during inflation, and during even minor accidents, individuals have been injured, some fatally. It is recognized that some form of control would be preferable, rather than disconnecting the airbags completely.
The principal function of an airbag during an accident is to fill the space between an individual an the interior structure of the vehicle. The airbag is inflated quickly with a selected gas, usually nitrogen but not necessarily, at speeds that are in the order of 200 milliseconds, or as fast as a human eye can blink.
Of course, present day airbags are arranged for a worst case condition. For instance, a 200 mile per hour airbag inflation velocity may be justified for a high speed, 65 mile per hour collision.
For a collision at a lower speed, however, the 200 mile per hour velocity of an inflating airbag is not necessary and can, in fact, cause injury to an occupant. A tailoring of the inflation velocity profile can reduce the risk of such injury to the occupant when the inflating bag strikes the occupant.
The necessary high speed of inflating the airbag also develops a force on impact with an individual, producing an injury. Present-day efforts to avoid this type of injury seem to be directed at developing some control over the rate of inflation for the airbag, but unless the inflation is accomplished quickly, there is a risk that it will be too late to prevent the individual coming into contact with the inside structure of the vehicle.
Previous efforts to avoid injury to individuals from airbags have taken many forms, some include the following.
For example, U.S. Pat. No. 5,564,743 to Marchant describes a housing with two chambers, one having a frangible section to rupture producing different levels of inflation.
U.S. Pat. No. 5,551,723 to Mahon et al. describes a valve arrangement to control the rate of gas flow as a form of airbag inflation control.
U.S. Pat. No. 5,435,594 to Gille describes a system for airbag inflation to protect an out of position occupant by a manifold coupled with two air bags.
U.S. Pat. No. 5,468,013 to Gille describes a manifold for controlling gas inflation between inner and outer airbags at different rates.
U.S. Pat. No. 4,213,635 to Inokuchi et al. describes a device to supply pressure to an airbag and a second device supply delayed pressure.